Carbamate-functional polyester polymer or oligomer having pendant carbomate groups

ABSTRACT

Polyester polymers having pendant carbamate groups are disclosed. The polymers are prepared by reacting a polyol having at least one pendant carbamate group with a polyacid to form a polyester having pendant carbamate groups.

FIELD OF THE INVENTION

This invention relates to polymers, and in particular to curable coatingcompositions that contain containing polymers.

BACKGROUND OF THE INVENTION

Polymers and oligomers having carbamate functional groups have been usedin a variety of curable compositions. Carbamate-functional acrylicpolymers are described, for example, in U.S. Pat. No. 5,356,669 and WO94/10211. These can be prepared by addition polymerization ofcarbamate-functional acrylic monomers or by transcarbamylation of ahydroxy functional acrylic with an alkyl carbamate. Carbamate-functionalpolyesters, prepared by transcarbamylation of a hydroxy-functionalpolyester, are described in JP 51/4124.

Polyesters are widely used in curable compositions such as coatingcompositions. These resins offer many beneficial properties, such asgood durability, good flexibility, good dispersibility in aqueoussystems through incorporation of appropriate ionic or nonionicstabilizing groups, impact resistance, good adhesion, and other physicalproperties such as stress release. One area of concern with polyesterresins for curable compositions has been the incorporation into theresin of sufficient levels of functional groups to achieve the desiredcure performance. Hydroxyl groups are commonly used as functional groupsin curable compositions, but polyester resins with pendant hydroxylgroups are difficult to prepare since any pendant hydroxyl groups wouldbe consumed by reaction with acid groups during formation of thepolyester. Hydroxyl functional groups are usually incorporated ontopolyester resins by the use of polyol capping agents like trimethylolpropane resulting in terminal OH groups, but no pendant OH groups. Suchresins provide only limited crosslink density upon cure. The crosslinkdensity may be increased somewhat by using branched polyesters, whichare prepared by the incorporation of trifunctional or higher functionalpolyols or polyacids in the polyester reaction mixture. However, thedegree of branching is often limited due to gelation. Low crosslinkdensity in curable polyester resin systems must often be compensated forby using higher molecular weight resins that more closely resemblethermoplastic compositions than thermoset compositions.

Carbamate-functional polyesters are described in JP 51/4124. Thisreference describes the preparation of polyesters having carbamateterminal groups by the transesterification of a typicalhydroxy-functional polyester with an alkyl carbamate.

Accordingly, the present invention is directed toward a new method ofpreparing polyester polymers or oligomers having pendant carbamategroups.

SUMMARY OF THE INVENTION

According to the present invention, a method of preparing a polyesterpolymer or oligomer is provided comprising reacting a polyol having atleast one pendant carbamate group with a polyacid to form a polyesterhaving pendant carbamate groups.

In another embodiment of the invention, there are provided polyesterpolymers or oligomers prepared by the above method.

In yet another embodiment of the invention, there are provided curablecoating compositions comprising the above-described carbamate-functionalpolyester and a curing agent that is reactive with carbamate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polyol having at least one carbamate group appended thereto can beprepared in a variety of ways. One method is to react a compound havinga plurality of cyclic carbonate groups with ammonia, ammonium hydroxide,or a primary amine to ring open the cyclic carbonate groups. Thisring-opening reaction converts each cyclic carbonate ring to a hydroxylgroup and a pendant carbamate group.

The compound having a plurality of cyclic carbonate groups can beprepared in several ways. One technique is to react a polyisocyanate ora polyanhydride with a hydroxyalkyl cyclic carbonate. Hydroxyalkylcyclic carbonates can be prepared by a number of approaches. Certainhydroxyalkyl cyclic carbonates like 3-hydroxypropyl carbonate (i.e.,glycerine carbonate) are commercially available. Cyclic carbonatecompounds can be synthesized by any of several different approaches. Oneapproach involves reacting an epoxy group-containing compound with CO₂,preferably under pressure with a catalyst. Useful catalysts include anythat activate an oxirane ring, such as tertiary amine quaternay salts(e.g., tetramethyl ammonium bromide), tin and/or phosphorous complexsalts (e.g., (CH₃)₃ SNI, (CH₃)₄ PI). Epoxides can also be reacted withβ-bytyrolactone in the presence of such catalysts. In another approach,a glycol like glycerine is reacted at temperatures of at least 80° C.(usually under reflux) with diethyl carbonate in the presence of acatalyst (e.g., potassium carbonate) to form a hydroxyalkyl carbonate.Alternatively, a functional compound containing a ketal of a 1,2-diolhaving the structure: ##STR1## can be ring-opened with water attemperatures of at least 60° C., preferably with a trace amount of acid,to form a 1,2-glycol, which is then further reacted with diethylcarbonate to form the cyclic carbonate.

Cyclic carbonates typically have 5-6-membered rings, as is known in theart. Five-membered rings are preferred, due to their ease of synthesisand greater degree of commercial availability. Preferred hydroxyalkylcyclic carbonates used in the practice can be represented by theformula: ##STR2## where R is a hydroxyalkyl group of 1-18 carbon atoms,preferably 1-6 carbon atoms, and more preferably 1-3 carbon atoms, and nis 1 or 2, which may be substituted by one or more other substituentssuch as blocked amines or unsaturated groups. More preferably, R is--C_(m) H_(2m) OH where the hydroxyl may be primary or secondary and mis 1 to 8, and even more preferably, R is --(CH₂)_(p) --OH where thehydroxyl is primary and p is 1 to 2.

The organic polyisocyanate that can be reacted with the hydroxyalkylcyclic carbonate is essentially any polyisocyanate and is preferably adiisocyanate, e.g., hydrocarbon diisocyanates or substituted hydrocarbondiisocyanates. Many such organic diisocyanates are known in the art,including p-phenylene diisocyanate, biphenyl 4,4'diisocyanate, toluenediisocyanate, 3,3'-dimethyl-4,4 biphenylene diisocyanate,1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate,2,2,4-trimethylhexane-1,6 diisocyanate, methylene bis (phenylisocyanate), 1,5 naphthalene diisocyanate, bis (isocyanatoethylfumarate), isophorone diisocyanate (IPDI), tetramethylxylenediisocyanate, and methylene-bis- (4 cyclohexylisocyanate). There canalso be employed isocyanate-terminated adducts of diols, such asethylene glycol, or 1,4-butylene glycol, etc. These are formed byreacting more than one mole of a diisocyanate, such as those mentioned,with one mole of a diol to form a longer chain diisocyanate.Alternatively, the diol can be added along with the diisocyanate.

While diisocyanates are preferred, other multi-functional isocyanatesmay be utilized. Examples are 1,2,4-benzene triisocyanate andpolymethylene polyphenyl isocyanate.

The polyisocyanate and hydroxyalkyl cyclic carbonate reaction can beperformed under conditions known in the art for the reaction of alcoholsand isocyanates.

Polyanhydrides that can be reacted with a hydroxyalkyl cyclic carbonateinclude any of a number of compounds well-known in the art, e.g.,hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, maleicanhydride, glutamic anhydride, 1,2,4,5-bis-anhydride cyclohexane. Theconditions for this reaction are generally at least 80° C., preferably98°-120° C., in the presence of a tin metal catalyst.

Compounds having a plurality of cyclic carbonate groups can also bereadily prepared by reaction of a polyepoxide with carbon dioxide toconvert the epoxy groups to cyclic carbonate groups. Polyepoxides arewell-known in the art. Useful polyepoxides include the trimethylolpropane that has been epoxidized by reaction with an epihalohydrin, andalso epoxy-novolacs. Oligomeric or polymeric polyepoxides, such asacrylic polymers or oligomers containing glycidyl methacrylate orepoxy-terminated polyglycidyl ethers, can also be used. Otherpolyepoxides, e.g., epoxy-novolacs, may also be used. As with otherpolyepoxides, epoxy-novolacs can be reacted with carbon dioxide to formthe cyclic carbonate compound.

Although linear polyesters will be based primarily on compounds havingtwo functional groups for the esterification reaction, cyclic carbonateswith a functionality higher than 3 are also contemplated to providebranched polyesters. For example, the isocyanate groups on adiisocyanate such as isophorone diisocyanate may be adducted with apolyol such as trimethylol propane to produce a tetrafunctional alcohol,which can be epoxidized with an epihalohydrin to produce atetrafunctional polyepoxide, which is in turn reacted with carbondioxide to form a tetrafunctional cyclic carbonate. Otherhigher-functionality polyepoxides, e.g.,tetrakis(4-glycidyloxyphenyl)ethane, may also be reacted with CO₂ toform poly-cyclic carbonates.

The compound having a plurality of cyclic carbonate groups is reactedwith ammonia, ammonium hydroxide, or a primary amine. This reaction isperformed under mild conditions (e.g., 0°-60° C. in water, methanol, orother known solvents. Reaction with ammonia or ammonium hydroxide yieldsa primary carbamate, and is preferred. Reaction with ammonia or ammoniumhydroxide yields a primary carbamate, and is preferred. Reaction with aprimary amine yields a secondary (N-substituted) carbamate. Thering-opening reaction of ammonia, ammonium hydroxide, or a primary aminewith the cyclic carbonate group yields a carbamate group as describedabove and also a primary or secondary hydroxyl group, which takes partin the polyester-forming reaction in the next step of the invention.This reaction product thus comprises pendant carbamate groups, andterminal hydroxyl groups.

Another technique to prepare a polyol having at least one pendantcarbamate group appended thereto is to react a hydroxyalkyl cycliccarbonate with ammonia, ammonium hydroxide, or a primary amine. Thisreaction is performed as described above with respect to the ringopening of the compound having plurality of cyclic carbonate groups. Theresulting compound has two hydroxyl groups and one pendant carbamategroup.

The pendant carbamate groups on the polyester of the present inventioncan be primary or secondary groups. Primary carbamate groups can berepresented by the formula: ##STR3## and secondary carbamate groups canbe represented by the formula: ##STR4## where R is substituted orunsubstituted alkyl of 1-8 carbon atoms, preferably 1-4 carbon atoms,and more preferably 1 carbon atom, or cycloaliphatic. It is to beunderstood that the terms alkyl and cycloalkyl are to includesubstituted alkyl and cycloalkyl, such as halogen-substituted alkyl orcycloalkyl or unsaturated group-substituted alkyl. Substituents thatwill have an adverse impact on the properties of the cured material,however, are to be avoided. Primary carbamates are formed in theabove-described ring-opening reactions of cyclic carbonates through theuse of ammonia or ammonium hydroxide as the ring-opening reactant.

According to the present invention, a mixture comprising the polyolhaving at least one pendant carbamate group and a polyacid is reacted toform a polyester. Polyacids useful in the practice of the invention maycontain about 2 to 34 carbon atoms in aliphatic or aromatic moieties,and at least 2, preferably no more than 4, carboxyl groups which may,alternatively, be present in the form of anhydride groups. The polyacidsmay be polyacids themselves or cyclic anhydrides of polyacids, which canbe ring opened by the carbamate-containing diol or other polyols duringthe polyester reaction to form acid groups for polyester condensation.Examples of useful polyacids include phthalic anhydride, terephthalicacid, isophthalic acid, adipic acid, succinic acid, glutaric acid,fumaric acid, maleic acid, cyclohexane dicarboxylic acid, trimelliticanhydride, azeleic acid, sebasic acid, dimer acid, pyromelliticdianhydride, substituted maleic and fumaric acids such as citraconic,chloromaleic, or mesaconic acids, and substituted succinic acids such asaconitic and iraconic acids. Mixtures of polyacids can be employed.

The polyester reaction mixture may also comprise additional polyols. Theamount of such additional polyol is determined by the desired level ofcarbamate functionality for the polyester. Useful polyols generallycontain more than 2, preferably 2 to about 10 carbon atoms, morepreferably about 2 to 8 carbon atoms, in addition to having 2 to about6, preferably 2 to about 4, hydroxyl groups. Some preferred examples ofthe polyols are one or more of the following: neopentyl glycol, ethyleneglycol, propylene glycol, butanediol, hexamethylemediol,1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,1,4-cyclohexanedimethanol, trimethylol propane, pentaerythritol,neopentyl glycol hydroxypivalate diethylene glycol, triethylene glycol,tetraethylene glycol, dipropylene glycol, polypropylene glycol, hexyleneglycol, 2-methyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol,1,5-pentanediol, thiodiglycol, 1,3-propanediol, 1,3-butanediol,2,3-butanediol, 1,4-butanediol, 2,2,4-trimethyl 1,3-pentanediol,1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, glycerol,trimethylolpropane, trimethylolethane, 1,2,4-butanetriol,1,2,6-hexanetriol, dipentaerythritol, tripentaerythritol, mannitol,sorbitol, methylglycoside, like compounds apparent to those skilled inthe art, and mixtures thereof. Depending on the properties desired forthe final resin, certain other polyols can be incorporated into thereaction mixture, such as fatty polyols, phenolic polyols (e.g.,hydroquinone, phenolphthalein, bisphenol A), oligomeric, or polymericpolyols (e.g., pre-formed polyester polyols). Additionally, othercomponents, such as reaction modifiers, catalysts, solvents, dispersingagents, and the like as is known in the art.

The proportions of the polyacid, polyol having pendant carbamate groups,and any other active compounds may be chosen so as to provide anacid-terminated polyester or a hydroxyl-terminated polyester. This canbe accomplished by utilizing a stoichiometric excess of polyacid orpolyol.

If water-solubility is desired, it is important to buildwater-stabilizing groups into the polyester. This can be accomplished byincorporating water-stabilizing polyether polyols into the reactionmixture so they are incorporated into the polyester or by utilizingdimethanol propionic acid as a polyol in the reaction mixture.

An intermediate polyester resin may be prepared having hydroxyl or acidterminal groups by the use of an excess of polyacid or polyol componentin the polyester reaction mix. The terminal groups of the resin may thenbe controlled by reaction of those terminal groups with an excess of acapping agent, as is known in the art. If the intermediate resin is acidterminated, a mono- or multi-functional alcohol may be used to terminatethe reaction (cap the free acid groups) at the desired stage (determinedby the viscosity and concentration of isocyanate groups present).Multi-functional alcohols, such as ethylene glycol, trimethylolpropaneand hydroxyl-terminated polyesters, can also be employed in this manner.If a resin with only carbamate functionality and no hydroxylfunctionality, the intermediate polyester resin is preferably cappedwith a monofunctional alcohol (e.g., n-butanol). Likewise, ahydroxyl-terminated intermediate resin can be capped by reaction with anexcess of mono- or polyfunctional acid.

Polyesterification reactions are normally carried out at temperaturesbetween 140° C. and 260° C., and for a time ranging from 3 to 15 hourswith or without the use of acid esterification catalysts such asphosphorous acid or toluene sulfonic acid present at levels of 0.01 to2.0 weight percent. The reaction is optionally carried out in thepresence of a solvent, such as an aromatic hydrocarbon, as is known inthe art. The reaction may be carried out as a single-stage reaction oras a multistage reaction such as a two-stage reaction. The polyestersthus produced generally have a number average molecular weight of from1000 to 60,000.

The polyester resin prepared according to the invention can beincorporated into a curable composition such as a coating composition.In a curable composition according to the invention, curing is effectedby a reaction of the carbamate-functional polyester component with acomponent (2) that is a compound having a plurality of functional groupsthat are reactive with the pendant carbamate groups on the polyester.Such reactive groups include active methylol or methylalkoxy groups onaminoplast crosslinking agents or on other compounds such asphenol/formaldehyde adducts, siloxane groups, and anhydride groups.Examples of curing agents include melamine formaldehyde resin (includingmonomeric or polymeric melamine resin and partially or fully alkylatedmelamine resin), urea resins (e.g., methylol ureas such as ureaformaldehyde resin, alkoxy ureas such as butylated urea formaldehyderesin), polyanhydrides (e.g., polysuccinic anhydride), and polysiloxanes(e.g., trimethoxy siloxane). Aminoplast resin such as melamineformaldehyde resin or urea formaldehyde resin are especially preferred.

A solvent may optionally be utilized in a curable composition used inthe practice of the present invention. Although the composition usedaccording to the present invention may be utilized, for example, in theform of substantially solid powder, or a dispersion, it is oftendesirable that the composition is in a substantially liquid state, whichcan be accomplished with the use of a solvent. This solvent should actas a solvent with respect to both the carbamate-functional polyester aswell as the curing agent. In general, depending on the solubilitycharacteristics of the components, the solvent can be any organicsolvent and/or water. In one preferred embodiment, the solvent is apolar organic solvent. More preferably, the solvent is a polar aliphaticsolvents or polar aromatic solvents. Still more preferably, the solventis a ketone, ester, acetate, aprotic amide, aprotic sulfoxide, oraprotic amine. Examples of useful solvents include methyl ethyl ketone,methyl isobutyl ketone, m-amyl acetate, ethylene glycol butylether-acetate, propylene glycol monomethyl ether acetate, xylene,N-methylpyrrolidone, or blends of aromatic hydrocarbons. In anotherpreferred embodiment, the solvent is water or a mixture of water withsmall amounts of co-solvents.

The curable composition used in the practice of the invention mayinclude a catalyst to enhance the cure reaction. For example, whenaminoplast compounds, especially monomeric melamines, are used, a strongacid catalyst may be utilized to enhance the cure reaction. Suchcatalysts are well-known in the art and include, for example,p-toluenesulfonic acid, dinonylnaphthalene disulfonic acid,dodecylbenzenesulfonic acid, phenyl acid phosphate, monobutyl maleate,butyl phosphate, and hydroxy phosphate ester. Strong acid catalysts areoften blocked, e.g. with an amine. Other catalysts that may be useful inthe composition of the invention include Lewis acids, zinc salts, andtin salts.

In a preferred embodiment of the invention, the solvent is present inthe curable composition in an amount of from about 0.01 weight percentto about 99 weight percent, preferably from about 10 weight percent toabout 60 weight percent, and more preferably from about 30 weightpercent to about 50 weight percent.

Coating compositions can be coated on the article by any of a number oftechniques well-known in the art. These include, for example, spraycoating, dip coating, roll coating, curtain coating, and the like. Forautomotive body panels, spray coating is preferred.

Any additional agent used, for example, surfactants, fillers,stabilizers, wetting agents, dispersing agents, adhesion promoters, UVabsorbers, HALS, etc. may be incorporated into the coating composition.While the agents are well-known in the prior art, the amount used mustbe controlled to avoid adversely affecting the coating characteristics.

The curable composition according to the invention is preferablyutilized in a high-gloss coating and/or as the clearcoat of a compositecolor-plus-clear coating. High-gloss coatings as used herein arecoatings having a 20° gloss (ASTM D523-89) or a DOI (ASTM E430-91) of atleast 80°. The curable composition according to the invention can alsobe used as the basecoat of a composite color-plus-clear coating.

When the coating composition of the invention is used as a high-glosspigmented paint coating, the pigment may be any organic or inorganiccompounds or colored materials, fillers, metallic or other inorganicflake materials such as mica or aluminum flake, and other materials ofkind that the art normally names as pigments. Pigments are usually usedin the composition in an amount of 1% to 100%, based on the total solidweight of components A and B (i.e., a P:B ratio of 0.1 to 1).

When the coating composition according to the invention is used as theclearcoat of a composite color-plus-clear coating, the pigmentedbasecoat composition may any of a number of types well-known in the art,and does not require explanation in detail herein. Polymers known in theart to be useful in basecoat compositions include acrylics, vinyls,polyurethanes, polycarbonates, polyesters, alkyds, and polysiloxanes.Preferred polymers include acrylics and polyurethanes. In one preferredembodiment of the invention, the basecoat composition also utilizes acarbamate-functional acrylic polymer. Basecoat polymers may bethermoplastic, but are are preferably crosslinkable and comprise one ormore type of cross-linkable functional groups. Such groups include, forexample, hydroxy, isocyanate, amine, epoxy, acrylate, vinyl, silane, andacetoacetate groups. These groups may be masked or blocked in such a wayso that they are unblocked and available for the cross-linking reactionunder the desired curing conditions, generally elevated temperatures.Useful cross-linkable functional groups include hydroxy, epoxy, acid,anhydride, silane, and acetoacetate groups. Preferred cross-linkablefunctional groups include hydroxy functional groups and amino functionalgroups.

Basecoat polymers may be self-cross-linkable, or may require a separatecross-linking agent that is reactive with the functional groups of thepolymer. When the polymer comprises hydroxy functional groups, forexample, the cross-linking agent may be an aminoplast resin, isocyanateand blocked isocyanates (including isocyanurates), and acid or anhydridefunctional cross-linking agents.

The coating compositions described herein are preferably subjected toconditions so as to cure the coating layers. Although various methods ofcuring may be used, heat-curing is preferred. Generally, heat curing iseffected by exposing the coated article to elevated temperaturesprovided primarily by radiative heat sources. Curing temperatures willvary depending on the particular blocking groups used in thecross-linking agents, however they generally range between 93° C. and177° C. The compounds according to the present invention are reactiveeven at relatively low cure temperatures. Thus, in a preferredembodiment, the cure temperature is preferably between 115° C. and 150°C., and more preferably at temperatures between 115° C. and 138° C. fora blocked acid catalyzed system. For an unblocked acid catalyzed system,the cure temperature is preferably between 82° C. and 99° C. The curingtime will vary depending on the particular components used, and physicalparameters such as the thickness of the layers, however, typical curingtimes range from 15 to 60 minutes, and preferably 15-25 minutes forblocked acid catalyzed systems and 10-20 minutes for unblocked acidcatalyzed systems.

The invention is further described in the following examples.

Example 1--Preparation of polyol having at least one pendant carbamategroup

A three neck round bottom flask was fitted with a coldfinger condenserdewar, stirrer, ammonia inlet tube fitted with porous fritted glass tipand thermocouple. This apparatus was then placed in a metal containerwhich was filled with dry ice, water, acetone and sodium chloride as acold bath in order to control the temperature of the reaction. Thisreactor was loaded with hydroxyalkyl cyclic carbonate (Glycar®) with anequal molar amount of methanol. The temperature of the reactioncomponents was dropped to 15° C. at which time ammonia gas was bubbledthrough the reaction until the temperature of the reaction increased to32° C. At this time the reaction was stirred and cooled back down to 15°C. This procedure was continued until a carbonate peek was no longerseen in the infrared spectrum. This should take approximately 12 hoursdepending on the batch size and ammonia concentration.

After all the Glycar® was converted to the glycol carbamate the reactorapparatus was converted so that a heated vacuum strip can be performed.The vacuum strip was started at room temperature to prevent bumping orover expansion of the system. The temperature was slowly increased(system permitting) to 80° C. under full vacuum 28 in Hg. the vacuumstrip was complete when the gas. chromatograph was clean of ammonia andmethanol.

Example 2--Preparation of linear aromatic/aliphatic polyester polyolwith pendant carbamate functional groups

A three neck round bottom flask was fitted with a perforated 5 platedistilling column, stirrer, adapter claisen with solvent trap 50milliliters, condenser, nitrogen inlet tube and thermocouple. Thisreactor was loaded with the following:

    ______________________________________                                        Ingredients          Weight                                                   ______________________________________                                        Dimer fatty acid Empol ® 1010                                                                  1612.34                                                  Toluene (azeotrope solvent)                                                                        100.00                                                   1,6 Hexane diol      673.14                                                   Isophthalic acid     462.80                                                   Carbamate glycol     227.51                                                   Dibutyltindilaurate   0.50                                                                         2976.29                                                  ______________________________________                                    

The agitator was started at low speed. Fifty grams of toluene wascharged to the collection trap and slowly heat the reaction to 137.7° C.Once the reaction reached 137.7° C. the reaction was held at thistemperature for two an one half hours (some azeotrope of toluene andwater will be seen). After the two an half hour hold increase thetemperature to 170° C. where a very strong azeotrope of toluene andwater will take place. The reaction temperature was held at 170° C. for8 hours at this time the first acid number should be taken. The acidnumber was then taken every hour until the reaction reached a valuebetween (5-10)AN or (0.089-0.178) milliequivalents per gram. After thereaction has extended to the predetermined acid number let the toluenecome over with the water until all the toluene was collected. Cool thereaction to 100° C. and add 800 grams of Exxate® 800 to the reaction andlet the batch continue to cool to room temperature.

Example 3--Preparation of linear aromatic/aliphatic polyester polyolwith pendant carbamate functional groups

A three neck round bottom flask was fitted with a perforated 5 platedistilling column, stirrer, adapter claisen with solvent trap 50milliliters, condenser, nitrogen inlet tube and thermocouple. Thisreactor was loaded with the following:

    ______________________________________                                        Ingredients          Weight                                                   ______________________________________                                        Dimer fatty acid Empol ® 1010                                                                  2022.71                                                  Toluene (azeotrope solvent)                                                                        100.00                                                   1,6 Hexane diol      673.14                                                   Isophthalic acid     499.35                                                   Carbamate glycol     136.35                                                   Dibutyltindilaurate   0.50                                                                         3378.03                                                  ______________________________________                                    

The agitator was started at low speed. Fifty grams of toluene wascharged to the collection trap and slowly heated to 137.7° C. Once thereaction reached 137.7° C. the reaction was held at this temperature fortwo an one half hours (azeotrope of toluene and water will be noticed).After the hold, the reaction temperature was increased to 170° C. wherea very strong azeotrope of toluene and water exists. The reactiontemperature was held at 170° C. for 8 hours, at this time the first acidnumber was taken. The acid number was taken every hour until thereaction reached a value between (5-8)AN or (0.089-0.143)milliequivalents per gram. After the reaction has extended to thepredetermined acid number let the toluene come over with the water untilall the toluene was collected. Cool the reaction to 100° C. and add 900grams of Exxate® 800 to the reaction and let the batch continue to coolto room temperature.

Example 4--Preparation of linear aliphatic polyester polyol with pendantfunctional groups

A three neck round bottom flask was fitted with a perforated 5 platedistilling column, stirrer, adapter claisen with solvent trap 50milliliters, condenser, nitrogen inlet tube and thermocouple. Thisreactor was loaded with the following:

    ______________________________________                                        Ingredients          Weight                                                   ______________________________________                                        Dimer fatty acid Empol ® 1010                                                                  2022.71                                                  Toluene (azeotrope solvent)                                                                        100.00                                                   1,6 Hexane diol      719.12                                                   Adipic Acid          499.35                                                   Carbamate glycol     136.35                                                   Dibutyltindilaurate   0.50                                                                         3478.03                                                  ______________________________________                                    

The agitator was started at low speed. Fifty grams of toluene wascharged to the collection trap and slowly heat the reaction to 137.7° C.Once the reaction reached 137.7° C., the reaction was held at thistemperature for four hours (azeotrope of toluene and water was seen).After the four hour hold, the temperature was increased to 170° C. wherea very strong azeotrope of toluene and water was seen. The reactiontemperature was held at 170° C. for 8 hours, at which the first acidnumber was taken. The acid number was then taken every hour until thereaction reached a value between (5-10)AN or (0.089-0.178)milliequivalents per gram. After the reaction had extended to thepredetermined acid number, the toluene was allowed to come over with thewater until all the toluene was collected. The reaction was cooled to100° C. and add 900 grams of Exxate® 800 to the reaction and the batchcontinued to cool to room temperature.

Example 5--Preparation of solventborne polyester/polyurethane withpendent carbamate functional groups

A three neck round bottom flask was fitted with a condenser, stirrer,nitrogen inlet tube and thermocouple. This reactor was loaded with thefollowing:

    ______________________________________                                        Ingredients             Weight                                                ______________________________________                                        Polyester polyol with pendant carbamate                                                               1732.49                                               functionality (see Example 1).                                                Methyl propyl ketone    362.69                                                Neopentyl glycol        176.52                                                Isophorone diisocyanate (IPDI)                                                                        651.70                                                Methyl ethyl ketone     143.00                                                ______________________________________                                    

After all of the above ingredients were added to the reactor thereaction mixture was heated to 99.8° C. As the reaction proceeded aslight exotherm was noticed and the reaction temperature rose to about107.0° C. After the exotherm, the reaction temperature was held at(107.0°-110)° C. for three hours where the first NCO numberdetermination was taken. The target value was (0.24-0.25) meq NCO/gramresin. When the NCO number was in this range then the addition of 101.68grams of TMP was added which was the capping stage of the reaction.After the addition of the TMP the reaction was held for 1.5 hours and afinal NCO number determination was taken. When the NCO number wasdetermined to be nonexistent the reaction was over an the reaction wascooled to 87.7° C. where 1036.23 grams of Exxate® 800 was added and thereaction was over.

Example 4--Preparation of waterborne polyester/polyurethane polymerswith pendant carbamate functional groups

A three neck round bottom flask was fitted with a condenser, stirrer,nitrogen inlet tube and thermocouple. This reactor was loaded with thefollowing:

    ______________________________________                                        Ingredients             Weight                                                ______________________________________                                        Polyester polyol with pendant carbamate                                                               1732.49                                               functional groups (see example 1)                                             Methyl propyl ketone    362.69                                                Neopentyl glycol        138.11                                                Isophorone diisocyanate (IPDI)                                                                        651.70                                                dimethylolpropionic acid                                                                               53.41                                                Methyl ethyl ketone     158.00                                                ______________________________________                                    

After all of the above ingredients were added the reaction mixture washeated to 99.8° C. As the reaction proceeded a slight exotherm occurredand the temperature rose to about 107.2° C. After the exotherm, thereaction temperature was held at (107.0°-110.0)° C. for three hourswhere the first NCO number determination was taken. The target value wasbetween (0.23-0.24) meq NCO/gram resin. When the NCO number was in thisrange then the addition of 92.99 grams of trimethylol propane (TMP) wasadded in the capping stage of the reaction. After the addition of theTMP the reaction was held for 1.5 hours and a final NCO numberdetermination was taken. When the NCO number was determined to benonexistent the reaction was over an the reaction was cooled to 87.0° C.where 200.34 grams of butylcellosolve was added. The reaction wasfurther cooled to 82.0° C. where 34.9 grams of dimethylethanolamine(DMEA) was added and mixed for one hour to complete the salting phase ofthe reaction. After the hold the reaction was cooled to 67.0° C. where50.47 grams of Exxate® 800 and 2867.41 grams of deionized (DI) water wasadded. After charging the DI water, mix the reaction mixture for twohours in order for complete dispersion of the resin in the aqueousphase.

The invention has been described in detail with reference to preferredembodiments thereof. It should be understood, however, that variationsand modifications can be made within the spirit and scope of theinvention.

What is claimed is:
 1. A method of preparing a polyester having pendantcarbamate groups comprising the steps of(a) reacting a compound having aplurality of cyclic carbonate groups with ammonia, ammonium hydroxide,or a primary amine to ring open the cyclic carbonate groups to form apolyol having at least one pendant carbamate group, and (b) reacting amixture comprising the polyol from (a) having at least one pendantcarbamate group appended thereto and a polyacid to form a polyesterhaving pendant carbamate groups.
 2. A method according to claim 1wherein the compound having a plurality of cyclic carbonate groups isprepared by reacting a hydroxyalkyl cyclic carbonate with apolyisocyanate or a polyanhydride.
 3. A method according to claim 1wherein the compound having a plurality of cyclic carbonate groups isprepared by reacting a polyepoxide with CO₂.
 4. A method according toclaim 1 wherein the compound having a plurality cyclic carbonate groupsis reacted with ammonia or ammonium hydroxide.
 5. A method of preparinga polyester having pendant carbamate groups comprising the steps of(a)reacting a hydroxyalkyl cyclic carbonate with ammonia, ammoniumhydroxide, or a primary amine to form a polyol having a carbamate groupappended thereto, and (b) reacting a mixture comprising the polyol from(a) having at least one pendant carbamate group appended thereto and apolyacid to form a polyester having pendant carbamate groups.
 6. Amethod according to claim 5 wherein the hydroxyalkyl cyclic carbonate isreacted with ammonia or ammonium hydroxide.
 7. A method according toclaim 1 wherein said mixture further comprises a compound having aplurality of hydroxyl groups.
 8. A method according to claim 1 whereinthe polyacid comprises an anhydride.
 9. A method according to claim 5wherein said mixture further comprises a compound having a plurality ofhydroxyl groups.
 10. A method according to claim 5 wherein the polyacidcomprises an anhydride.
 11. A polyester that is the reaction productof(a) a polyol that is the reaction product of:(1) a compound having aplurality of cyclic carbonate groups, and (2) ammonia, ammoniumhydroxide, or a primary amine, (b) a polyacid.
 12. A polyester accordingto claim 11 wherein component (2) is ammonia or ammonium hydroxyide. 13.A polyester according to claim 11 wherein the compound (1) is thereaction product of a hydroxyalkyl cyclic carbonate and a polyisocyanateor a polyanhydride.
 14. A polyester according to claim 11 wherein thecompound (1) is the reaction product of a polyepoxide and CO₂.
 15. Apolyester that is the reaction product of(a) a polyol that is thereaction product of:(1) a hydroxyalkyl cyclic carbonate, and (2)ammonia, ammonium hydroxide, or a primary amine, and (b) a polyacid. 16.A polyester according to claim 15 wherein component (2) is ammonia orammonium hydroxide.
 17. A polyester according to claim 11 wherein saidmixture further comprises a compound (c) having a plurality of hydroxylgroups.
 18. A polyester according to claim 15 wherein said mixturefurther comprises a compound (c) having a plurality of hydroxyl groups.19. A curable coating composition comprising:(1) a polyester that is thereaction product of a mixture comprising:(a) a polyol having at leastone pendant carbamate group, and (b) a polyacid, and (2) a curing agenthaving a plurality of groups that are reactive with carbamate.
 20. Acurable coating composition according to claim 19 wherein the curingagent is an aminoplast.
 21. A curable coating composition according toclaim 20 wherein the aminoplast is a melamine resin.
 22. A curablecoating composition according to claim 19 wherein the compound (1)(a) isthe reaction product of:(i) a compound having a plurality of cycliccarbonate groups, and (ii) ammonia, ammonium hydroxide, or a primaryamine.
 23. A curable coating composition according to claim 22 whereincomponent (ii) is ammonia or ammonium hydroxide.
 24. A curable coatingcomposition according to claim 19 wherein the compound (1)(a) is thereaction product of:(i) a hydroxyalkyl cyclic carbonate, and (ii)ammonia, ammonium hydroxide, or a primary amine.
 25. A curable coatingcomposition according to claim 24 wherein component (ii) is ammonia orammonium hydroxide.